Selective separation of ores



L. J. O MALLEY SELEGTIVE SEPARATION OF ORES Dec. 20, 1932.

Filed June 14, 1930 P'atented Dec. 20, 1932 UNITED STATES PATENT OFFICE LOUIS J. O'MALLEY, OF lBOS'Il'ON, EASSACEUSETTS SELEGIIVE SEI'ABATION' OF ORE&

Application filed J'e 14,

My invention relates to methods of and apparatus for separating ores by froth fletation.

The invention will be best understood from the following description of an example of the practice of the method and from the accompanying drawing of one embodiment of apparatus for use m the practice of said method.

In the drawing Fig. 1 is a longitudinal section of a Fahrenwald type flotation machine having applied thereto a pair of electrodes for improving the separation of the orein accordance with the invention; e r

Fig. 2 is a section on the line 2-2 of F ig. 1; and

Fig. 3 is a. diagram illustrating schematcally a bubble with an adhering ore particle.

Referring to the drawing, the flotation mac'hine illustrated comprises a container 1 for the ore pulp and frothing liquid, the container having a submerged partition 3 which provides an auxiliary chamber 5. At` the ower end of the chamber 5 is a pump impeller 7 separated from the body of said chamber by a hood and baflie arrangement 9. The impeller 7, as shown, is rotated by a shaft 11 which extends' vertically upward to the exterior of the container and is driven by an suitable source of power. impeller is effective to agitate the contents of the container 1, drawing the liquid and Suspended ore through the passage 10 and forcing them Upward through the chamber '5 and causing the arrows.

As shown, surrounding the shaft 11 is a tube 13 placed in communication with the 'gtmosphere above the surface of the liquid Y a Conduit 15, which latter may be provded with a valve 17. In operationthe impeller ;9 causes 'atmospheric air to be drawn through the Conduit -15 and tube 13 and to discharge into the liquid for mixing with and aerating the same, the amount of air admitted bein controlled bythe valve 17.

The meta -value-bearing froth thus formed collects on the surface of the liquid, said sur- `R'otation of the them to circulate as indicated by 1930. serial No. 481,()93.

face indicated at 19, and discharges from the container through a spout 20.

Accordin to one form of the invention, the froth may %e caused to pass between electrodes 21 and 23, "the electrode 23 as shown being positioned adjacent the surface of the liquid and the electrode 21 being positioned above said surface. As illustrated, the two electrodes may be adjustabl Secured in selected positions lon itudinal y of a rod 25 of insulating materia say hard rubber, by y means of set screws 27, said rod being carried by a bracket 29 secured to the walls of the container. As shown, to the upper electrode 21 is Secured a wire 31 leading to one terminal of a suitable source of electromotive force, while the opposite electrode 23 is connected to the other terminal of said source by an insulated wire 33-, which latter may be carried in the longitudinally extending slot 35 formed in the rod 25. Preferably-a direct current source of electromotive force is employed, although beneficial results willbe secured by employment of an alternating current source, particularly when the latter is of rather low frequency, say in the order of 25 cycles or less per second. i

Preferably the electrodes are placed so that the rising ol bubbles from the chamber 5 as they reach the surface of the liquor are within the electrostatic field surrounding the electrodes. In the practice of the invention I have found that action of the electrodes 21 and 2.3 will increase the recovery of the re. F or example, in treatin Southeast Missouri: galena, which is essenta ly galeria with traces of. sphalerite, 'containing various impurities principally iron sulphide, andgssay'ing about 5% lead, the total recovery of galera under favor 'able conditions is iicr'eased'to about 77 .6% of the entire lead present When the electrodes are charged, as against a' total recovery of 588% of' theentire'lead present when the electrodes are `not employed, or if employed are not charged. 'i

It will be understoodthat the ore before treatment is first ground, for example, with the above mentioned ore ground sufliciently *to pass it through a 75 mesh screen, While the treating liquor has added thereto known reagents to depress the substances which are to remain in the tailings. For example, with the above ore, when the galena is to be separated, in which case the sphalerite (ZnS) and iron sulphide (FeS) are to remain in the tailings, the liquor may have added thereto the following reagents for 1000 parts of ore:

Parts Sodium carbonate 2.20 Sodium cyanide 0,09 Zincsulphate a 0.28 Potassium Xanthate 0.045 Thiocarbanild 0.035 Pine oil (General Naval Stores No.

It will be understood that with the above reagents the oily substances in combination with agitation and aeration cause the production of a froth consisting essentially of. oil bubbles to which adhere the particles of ore. The water content is not critical, but preferably in the above example about 18 parts of water are used for each part of ore.

Preferably the electrodes are of relatively large area or are otherwise formed to produce an extensively distributed field, for ex ample, in a laboratory size flotation machine having a Capacity of 1000 grams of ore and 9 liters of water satisfactory results will `be produced with electrodes about 4 inches 'square positioned substantially as shown in the drawing, with a potential difl'erence between the electrodes of about 220 volts direct current, and with the upper electrode touching the to'p surface of the froth and lower electrode about touching the surface of the liquor. It will be understood in this connection that the layer of froth in a machine of this size will ibe from about g; to 4: inches thick depending upon the conditions of operation. Under these conditions in the aboveexample the current flow between the electrodes will vary from 1.5 to 0.1 amperes.

It will be* understood, as commonly practised in the art of ore separation by froth flotation, that by employing suitable known reagents selected mineral contents of an ore can be separated in a similar manner to that in which the galena is separated in the above example, and that the invention is applicable to various ores capable of being separated by froth flotation. 4 v

Applicant for example', is separated the particle P of this mineral, Fig. 3, adheres to the oil bubble B something after themanner indicated by s .explanation of the above 'phenomena is that when the lead sulphide,

or intermittentl positive by use of an alter nating source o electromotive force, and the electrode 23 con'tinuously or intermittently negative, each bubble with its particle is -drawn or impelled upward from the surface of the liquid to increase the concentration. Applicant however advances this theory merely as explanatory of the phenomena which occurs, actual tests demonstrating the fact that charging the electrodes as above indicated increases the amount of the concentrate. For example, treating 327 grams of the 'above mentioned ore, with the electrodes charged at a potential of 220 volts direct current as above described, 41.92 grams of lead sulphide concentrate were recovered, while with the same ore, with the electrodes not charged, but 28.2 grams of concentrate were recovered,'in each case the concentrate recovered as saying exactly the same percentage of lead. lVith a charge on the electrodes the recovery of lead sulphide from the ore is therefore about 7 7.6% as compared to 588% with the electrodes uncharged. Apparently,

electrical conductivity of the froth is necessary for the 'occurrence of the above phenomena, but so far as known to applicant all froths produced in flotation processes possess this property.

It will be understood that wide deviations may be made from the above described examples of method, apparatus and materials, without departing from' the spirit of the invention. i i

I claim: 4

1. The processof ore separation which conprises subjecting u an ore pulp to froth flotation to produce a metal-value-bearing froth over the-froth liquor, and electrically attracting the metal-value-bearing fractions of said froth u ward relative to the surface of said liquor ycausing the froth to pass between electrodes having opposite electrical charges at a relatively high potential difference, one of which electrodes is above the surface of the liquor in electrical contact with the froth. I

2.- The process of selective sulphide ore separation which comprises subjecting' an ore pulp to froth fiotationf to produce a sul-' phide bearing ;froth. ;ov'f the pulp liquor, I and electrically attracti'ng the sulphide-bear ;ing fractions of said :froth upward relative to the surface of theliquor by causingthe froth. to pass between 'electrodes having opposite electrical charges at a`relatively high potential difference, one of which electrodes is above the surface of the liquor in electrical contact with the' froth;

3. The process of separating galena from ore 'containing other mineral's which comprises subjecting an ore pulp to froth flotation to produce a galena bearingf'roth, and electrically attracting the' galena-bearing fractions of said froth upward relative'to the surface of the liquor by causing the froth to pass between electrodes having op site electrical charges at a relatively high potential' difference, the electrode with a sitive charge being above the surface of the liquor in electrical contact with the frot 4. Apparatus for separating ores by froth flotation having, in combination, a container for ore pulp comprising a froth producing liquor, means for aerating said pulp to form on the pulp-.liquor a layer of metal-valuebearing froth and a pair of op osed electrodes, one &dJflCIlt the surface o the liquor and the other carried above said surface in substantially insulated relation to the li uor.

5. Apparatus for separating ores by oth flotation having, in combination, a container for ore pulp comprising a froth 1p'oducing liquor, means for aerating said pu p to form on the pulp liquor a layer of metal-valuebearing froth, and a pair of opposed platelike electrodes of material area, one ad acent the surface of the liquor in substantially parallel relaton thereto and the other carried above said surface in substantially insulated relation to the liquor.

6. Apparatus for separating ores by froth flotationhaving, in combinaton, means for agitating ore with a froth producing liquor to produce ore pulp, means for aeratmg said ore pulp to form on the pulp liquor a layer of metal-value-bearing froth, and a pair of opposed electrodes between which the froth is adapted to pass, one of said electrodes being adjacent the surface of the liquor and the other being carried above said surface in substantially insulated relation to the liuor.

7 Apparatus for separating ores by roth flotation having, in combinaton, means for agitating ore with a froth producing liquor to produce ore pulp, means for aeratng said ore pulp to form on the pulp liquor a layer of metal-value-bearn froth, and a pair of opposed platelike e ectrodes of material area between which the froth is adapted to pass, one of said electrodes being adjacent the surface of the liquor in substantially parallel reltion thereto and the other being carried above said surface in substantially insulated relation to the liquor.

8. The process of ore separation which comprises -subjecting an ore pulp to froth flotation to produce a metal-value-bearing froth over the pulp liquor, and impressing suflicient electrical charge attract the metal-valve-bearing fractions of the latter upward relative to the surface of the liquor.

9. The process of ore separation which comprises agitating ore with a froth producing liquor to produce ore pulp, aerating said pulp to produce a metal-value-bearing froth over said liquor, and impressing sufiicient clcctrcal charge on the froth to attract the on the froth to metal-value-bearing fractions of the letter upward relatve to the surface of said liquor. In testimony whereof, I have signed my name to this specification.

. LOUIS J. O'MALLEY.

CERTIFICATE' OF CORRECTON.

December 20, 1932.

Patent No. l,89l,776.

` .LoUs J. O'MALLEY.

It is hereby certf ied ,tha t error appears in the printed specifieation of the above numbered patent requiring correction as follows: ,Page 2. 'line 104, ela-im l, for "froth" read "pul'p"; and that' the said Letters Patent should be read with this correction the'reii that the same may confo-'m to the record of the case in the Patent Office.

Signed and seled this' 7th day of February, A. D. 1933.

M. J. Moore. (Seal) Acting Commissioner of Patents.

CERTIFICATE OF GORREGTION.

Patent No. 1,891,776. December 20, 1932.

LOUIS J. O'MALLEY.

It is hereby certed that the Certificate of Correction issued February 7, 1933, was erroneously drawr as to the word "frcth" and that this certificate should have read as foliows; page 2, line 104, claim 1, for "frcth", second occurrence, read "pu1p"; an that the said certificate should be read with this correction theren that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of February, A. D. 1933.

M. J. Moore,

(Seal) Acting Commissione' ot' Patents, 

